Comparative Allometry and Sexual Behavior of Four Fruit Fly Species in the Tribe Ceratitidini (Diptera: Tephritidae)

Abstract

Sexual dimorphisms in four related species of tephritid flies were shown to be associated with differences in sexual behavior. In two species, Ceratitis capitata and C. catoirii, males and females approach closely head to head and apparently touch aristae, and the male buzzes his wings, probably fanning pheromone toward the female; the males were found to have longer aristae with fewer microsetae, and larger posterior areas of their wings than do females. These dimorphisms were absent in the other two species, C. rosa and Neoceratitis cyanescens, which court at a longer distance and in which the male does not fan pheromone toward the female prior to mounting. All three pairs of legs were proportionally longer in the males of all four species. None of the other sexually dimorphic male signalling traits showed the positive allometric slopes predicted by some theories.

Sexual selection, phenotypic variation, and allometry in genitalic and non-genitalic traits in the sexually size-dimorphic stick insectMicrarchus hystriculeus

“…Negative static allometry is typically indicative of stabilizing sexual selection. As Bonduriansky () noted, viability traits that have been modified or co‐opted into secondarily serving sexual functions tend to have negative allometry or isometry (Eberhard, ; Briceno, Eberhard & Quilici, ; Bonduriansky, ) versus dedicated sexual structures that exhibit positive allometries (Kodric‐Brown et al ., ). This explanation certainly applies to the legs of stick insects because their predominant mode of locomotion for this wingless insect is walking.…”

Sexual Selection and Allometry: A Critical Reappraisal of the Evidence and Ideas

“…Although the small number and limited phylogenetic range of examples preclude a meaningful quantitative meta‐analysis, 10 of the 12 studies reviewed report negative allometry or isometry in some or all of the sexually selected traits examined. The positive allometry hypothesis is contradicted for signal and weapon traits (Cuervo and Møller 2001; Eberhard 2002a, b; Briceño et al 2005; Bonduriansky 2006), as well as for grasping traits (Tseng and Rowe 1999) and genital traits (Kelly et al 2000; Jennions and Kelly 2002; Hosken et al 2005; Bertin and Fairbairn 2007; also see Eberhard et al 1998). Second, even traits that are known to be under directional sexual selection do not necessarily evolve positive allometries (Bertin and Fairbairn 2007).…”

“…Briceño et al (2005) examined the allometries of 18 morphological traits in four species of tephritid flies, including head, antenna, and foreleg traits involved in sexual competition among males. Although virtually all traits were sexually dimorphic, none exhibited positive allometry in either sex.…”

“…In addition, the evidence illustrates that trait “exaggeration” can involve either an increase in allometric slope, or an increase in allometric intercept (resulting in a body size independent sexual dimorphism), or both. Sexual dimorphism without positive allometry is commonplace in secondary sexual traits within the groups included in this review (e.g., birds: Cuervo and Møller 2001; flies: Eberhard 2002a, b; Briceño et al 2005; Bonduriansky 2006; water striders: Tseng and Rowe 1999), suggesting that sexual selection often acts on the allometric intercept rather than the allometric slope.…”

Static allometry in two species of neotropical stalk‐eyed fly

“…There is also growing empirical evidence that sexually selected traits, especially in insects, do not always show positive allometry. For example, non‐positive scaling relationships have been found in the secondary sexual traits of drosophilids (Eberhard, ), tephritids (Briceño, Eberhard & Quilici, ), piophilids (Bonduriansky, ), stag beetles (Pomfret & Knell, ), earwigs (van Lieshout & Elgar, ) and dobsonflies (Ramírez‐Ponce, Garfias‐Lozano & Contreras‐Ramos, ). Given this controversy, it is important not only to investigate allometric slopes across a broad range of taxa, but also to assess the allometry of a variety of traits within individuals, including nonsexual traits.…”